Change function calls count to use a monotonic counter

[gagbo]

Description

• Update autometrics-shared submodule
• fix(otel): change function calls counter type

Fixes issue #37

Checklist

• [x] The CHANGELOG is updated.
• [x] The open-telemetry example in repository works fine:
  • the docker compose file is valid
  • the application compiles and run
  • alerts are getting triggered in Prometheus